CN100476167C

CN100476167C - Exhaust gas filtering system for internal combustion engine

Info

Publication number: CN100476167C
Application number: CN 200510129451
Authority: CN
Inventors: 奥川伸一朗; 小岛和雄
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2004-12-08
Filing date: 2005-12-08
Publication date: 2009-04-08
Anticipated expiration: 2025-12-08
Also published as: CN1786430A

Abstract

In order to restrict an over-temperature-rising of a diesel particulate filter (DPF 3), an electronic control unit (ECU 6) computes a flow rate of the exhaust gas flowing through the (DPF 3) so that temperature of the (DPF 3) is kept at a temperature in which the (DPF 3) can be regenerated. By adjusting a position of a throttle valve (42), a fresh air flow rate is adjusted so that the flow rate of the exhaust gas flowing through the (DPF 3) is equal to a target flow rate of the exhaust gas.

Description

The exhaust gas filtering system that is used for internal-combustion engine

Invention field

The present invention relates to a kind of exhaust gas filtering system that has particulate filter in discharge pipe, its excess temperature at the regeneration period restriction particulate filter of particulate filter rises.

Background technique

Exhaust (exhaust gas) filtration system (it is called as DPF) with the diesel particulate filter in the discharge pipe that is configured in diesel engine is well known.DPF catches and is included in from the particulate in the exhaust of diesel engine (it is called as PM).By the DPF that periodically regenerates of the PM according to this accumulation of PM amount burning of accumulation, wherein to measure be to estimate according to the pressure reduction between the upstream and downstream of DPF to the PM of this accumulation.

JP-2004-068804A (US-2003/0230060A1) illustrates the problem of exhaust gas filtering system, and promptly the excessive temperature of DPF rises.The flash fire of DPF of accumulation makes the temperature of DPF sharply rise, to such an extent as to it causes the infringement of DPF and catalyzer that DPF supported rotten.Especially when the temperature of the exhaust that flows into DPF since the high load driving of motor compare when higher, perhaps when the flow velocity of the exhaust by DPF by making that by means of its regenerative operation when reducing sharp under the very high situation of dpf temperature, the excess temperature of DPF rises and certainly will occur.As shown in Fig. 2 A, this is because the thermal exposure HRAQ that is radiated the exhaust from DPF reduces sharp, thereby increases the temperature of DPF sharp.

For limit temperature rises, even if operate the heat HREQ that from exhaust, is sent to DPF to reduce, for example, delivery temperature is reduced or unburned HC is stopped to be provided for DPF, the temperature that also is difficult to the whole DPF of restriction rises, because the downstream part of DPF receives heat via the exhaust of flowing through wherein from the upstream portion of DPF.Must increase the air displacement that flows through DPF,, rise with the temperature of restriction DPF downstream part so that increase the HRAQ enter among the exhaust.JP-2004-068804A illustrates a system, wherein when excessive temperature rises generation, increases the air displacement that flows into DPF.

Yet when the exhaust flow velocity increases when too high at its regeneration period, the temperature of DPF upstream portion is reduced significantly.Thus, fuel is wasted and is used for increasing once more the temperature of DPF, to such an extent as to the fuel economy variation.

Brief summary of the invention

In view of the foregoing, provided the present invention, and the object of the present invention is to provide a kind of exhaust gas filtering system, wherein rise and suppress and controlled the flow velocity of the exhaust of flowing through DPF well because the temperature of the upstream portion of DPF reduces the such mode of fuel economy variation that causes according to the excess temperature of the downstream part that suppresses DPF.

According to the present invention, a kind of exhaust gas filtering system that is used for internal-combustion engine has the particulate filter that is used to catch the particulate that is included in exhaust, and temperature rising control gear, this temperature rising control gear is used to increase the temperature of particulate filter, and the temperature of particulate filter is remained on predetermined temperature.Temperature rising control gear comprises object gas condition computing device, be used to calculate the goal condition of the exhaust of flowing through particulate filter, heat is transmitted so that the temperature of particulate filter is maintained at this predetermined temperature between particulate filter and exhaust in this goal condition.Temperature rising control gear comprises the gas flow rate control gear, is used for according to obtaining the flow velocity that the such mode adjustment of this goal condition is flow through the exhaust of particulate filter.Thus, exhaust increment quantitatively is limited, and the excess temperature of particulate filter rises and is limited, and the fuel economy variation also is limited.

Description of drawings

From the detailed description of making below with reference to accompanying drawing, the present invention other purpose, that feature and advantage will become will be more clear, wherein identical part represented by identical reference number, and wherein:

Fig. 1 is the schematic representation of an exhaust gas filtering system;

Fig. 2 A is the sequential chart of variation that is used to explain the regeneration temperature of DPF;

Fig. 2 B is the sequential chart that is used to explain according to the variation of the regeneration temperature of DPF of the present invention;

Fig. 3 is one to be used to explain in order to keep the temperature of DPF, the figure of the computational methods of excessive and not enough heat;

Fig. 4 is one to be used to explain in order to keep the maximum temperature of DPF, the figure of the computational methods of excessive and not enough heat;

Fig. 5 is a figure that the interior temperature distribution of DPF is shown;

The sequential chart of Fig. 6 controlling method that to be a flow velocity that is used to explain wherein exhaust increase according to slip rate and car speed;

Fig. 7 is one the flow chart of wherein adjusting the controlling method of the flow velocity that flows through DPF is shown;

Fig. 8 A is a flow chart that is used to explain the method for the temperature distribution of wherein estimating DPF;

Fig. 8 B is a chart that cell heat budget computation model is shown;

Fig. 9 is a Block Diagram that is used to calculate the object gas flow velocity of exhaust;

Figure 10 is the flow chart of the feedback control of a gas flow rate that live gas is shown;

Figure 11 is one the flow chart that the gas increment is determined method is shown; And

Figure 12 is a flow chart that the gas flow rate increment method is shown.

DETAILED DESCRIPTION OF THE PREFERRED

Embodiments of the invention are described below with reference to the accompanying drawings.

(first embodiment)

The exhaust gas filtering system that is used for diesel engine is described below.Fig. 1 is a schematic representation that the exhaust gas filtering system that is used for diesel engine is shown.Discharge pipe 2 comprises the first discharge pipe 2a and the second discharge pipe 2b.Diesel particulate filter (DPF) 3 is arranged between the first discharge pipe 2a and the second discharge pipe 2b.This DPF 3 has well-known structure, wherein is molded into cellular structure such as the such refractory of steinheilite, and this cellular structure has a plurality of cells that form the exhaust passage.Each end of cell is alternately closed, so that each cell only has inlet opening and exit orifice one of them at its opening end.The exhaust of motor 1 is introduced into DPF 3, so that this exhaust enters the inlet opening of a cell, is provided for next cell by corresponding porous wall, and is discharged from by the exit orifice of this next one cell.When the porous wall of each respective cell is passed through in exhaust, filter and collect the particulate (PM) that is included in the exhaust by DPF 3.

The oxidation catalyst that DPF 3 supports on it, the hydrocarbon (HC) that flows through discharge pipe 2 by this oxidation catalyst is burned, to increase the temperature of exhaust and DPF 3 effectively.As selection, DPF 3 can not have oxidation catalyst thereon, and perhaps oxidation catalyst can be disposed in the upstream of DPF 3.

First exhaust gas temperature sensor 51 and second exhaust gas temperature sensor 52 are provided in the first discharge pipe 2a and the second discharge pipe 2b respectively.First and second exhaust gas temperature sensors 51,52 detect upstream temperature and the downstream temperature of DPF 3, and are electrically connected with ECU (electronic control unit) 6, to send testing signal to ECU 6.Airometer (air inlet sensor) 41 is provided in suction tude 4, represents that with transmission the signal of induction air flow ratio is to ECU 6.Throttle valve 42 is provided at the downstream of airometer 41, increase/minimizing induction air flow ratio when receiving order from ECU 6.Air inlet pressure sensor 43 is provided in the suction tude 4, to detect the suction pressure in throttle valve 42 downstreams.

Suction tude 4 communicates by EGR the pipe 71 and first discharge pipe 2a that is equipped with EGR valve 7.When receiving command signal from ECU 6, EGR valve 7 is adjusted the air displacement that is recycled to suction tude 4 from the first discharge pipe 2a.The compressor 91 of turbosupercharger is provided between airometer 41 and the throttle valve 42.Compressor 91 mechanically is connected with turbine 92 in being equipped in the first discharge pipe 2a by the axle (not shown).Turbosupercharger has well-known structure.Exhaust gas drive turbine 92 is with rotary compressor 42.Compressor 42 compressions are provided for the air inlet of motor 1.Turbine 9 has the adjustable nozzle (not shown), and its drive condition according to motor 1 is controlled the position of spout blade (VNT: not shown), to adjust boost pressure.

Differential pressure pickup 8 is connected to the first and second discharge pipe 2a, 2b, so that detect the particle number of the accumulation of being caught by DPF 3.The particle number of the accumulation of being caught by DPF 3 is hereinafter referred to as QAPM.One end of differential pressure pickup 8 is connected to the first discharge pipe 2a by the first pressure inlet tube 81, and the other end of sensor 8 is connected to the second discharge pipe 2b by the second pressure inlet tube 82.Differential pressure pickup 8 sends the signal of the pressure reduction between the upstream and downstream of representing DPF 3 to ECU 6.This pressure reduction is hereinafter referred to as DPF pressure reduction.

ECU 6 be connected such as the such sensor (not shown) of accelerator position sensor and engine speed sensor, with the drive condition of detection of engine 1.ECU 6 controls suitable fuel injection amount, fuel injection timing and fueling injection pressure according to the drive condition of motor 1, sprays to carry out suitable fuel.The regeneration control of ECU 6 control DPF 3.When QAPM surpassed predetermined value, DPF 3 was heated by the heating equipment (not shown), with the PM of burning accumulation.The regenerative process of DPF 3 is described below.

Estimate QAPM based on the DPF pressure reduction that is detected by differential pressure pickup 8.Under the constant situation of air displacement, DPF pressure reduction increases along with the increase of QAPM.Based on this relation between DPF pressure reduction and the air displacement, can estimate QAPM.Perhaps, calculate the discharge amount of PM, then this discharge amount is carried out integration to estimate QAPM based on the drive condition of motor.These estimation approach can be combined.

Heating equipment sprays (post fuel injection) such as later stage fuel specifically, postpones fuel injection timing, throttle valve 42 enter throttling, increase the EGR quantity of EGR valve 7, and the interstage cooler bypass.The oxidation reaction of the unburned HC of this heating equipment by offering discharge pipe 2 is produced heat.Temperature from the exhaust of motor 1 is increased.Thus, the exhaust that is in high temperature is provided for DPF 3.

ECU 6 control heating equipments maintain DPF 3 in the predetermined regeneration temperature, with by operating this heating equipment DPF 3 that regenerates.This is equivalent to temperature rising control gear.Predetermined regeneration temperature (target temperature that is used to regenerate) can be constant, and for example, 650 ° of c perhaps can progressively change according to QAPM.Under the situation that target temperature changes, target temperature is set to lower than preset value, and to keep safety during very big relatively early stage of QAPM, increase target temperature when QAPM reduces can effectively be regenerated whereby then.

Temperature rising control gear control temperature rising operation amount and control flows are crossed the flow velocity of the exhaust of DPF 3, so that DPF 3 is remained on the object regeneration temperature.That is to say that object gas flow velocity computing device calculates the target exhaust flow velocity, so that DPF 3 is maintained at the object regeneration temperature.Exhaust current velocity controller control flows is crossed the flow velocity of the exhaust of DPF 3, so that the flow velocity of exhaust is consistent with the object regeneration temperature.

In the conventional controlling method shown in Fig. 2 A, when the drive condition of the motor regeneration period at DPF3 (for example changes, slow down) time, the flow velocity of exhaust (FREG) is increased sharp, rises to excess temperature elevated areas (OTRA) sharp with the temperature with DPF 3.This is that (the inner heat that produces of HREQ+DPF=HRAQ) become another condition is sent to the heat of exhaust that flows through DPF 3 and is reduced sharp in this another condition because of the constant condition of regeneration temperature.Thus, the summation of the inner heat that produces of HREQ and DPF surpasses HRAQ, to such an extent as to the temperature of DPF 3 is increased.The inner heat that produces of DPF is called IGH hereinafter.

For fear of such a case,, also should specified flow cross the flow velocity of the exhaust of DPF 3, to set up the following equation shown in Fig. 2 B even if the drive condition of motor changes.

HREQ+IGH＝HRAQ

That is to say that control is sent to heat of exhaust from DPF 3, so that keep predetermined regeneration temperature.

Object gas flow velocity computing device calculates the unnecessary and not enough heat of the temperature of keeping DPF 3, and calculates and the corresponding object gas flow velocity of this unnecessary and not enough heat.Particularly, as shown in Figure 3, calculate this unnecessary and not enough heat Δ Q based on following equation.

ΔQ＝Qr-Qb

Qr represents because the total amount of heat that produces in DPF 3 that HC burning and PM burning cause.Qb represents the temperature of DPF is increased to the required heat of object regeneration temperature (for example, 650 ° of c) from delivery temperature.According to calculating thermal exposure (HRAQ) Qout with following equation.

Qout＝Qex-Qin

Qin represents from the heat that exhaust had of DPF 3 outflows.Qex represents to flow into the heat that exhaust had of DPF3.Here, represent to flow at Tin under the situation of temperature of exhaust of DPF 3, Tex represents the temperature of the exhaust of flowing out from DPF 3, and Mgas represents the flow velocity of exhaust, and Cp represents the specific heat of exhaust, sets up following equation.

Qex＝Cp×Mgas×Tex

Qin＝Cp×Mgas×Tin

Thus, represent the flow velocity Mtrg of exhaust by following equation, wherein Qout equals Δ Q.

Mtrg＝ΔQ/{Cp×(Tex-Tin)}

Mtrg is defined as the target flow velocity of exhaust.

Control the flow velocity of exhaust according to the mode that becomes the target flow velocity, consistent with the heat that toilet shifts with unnecessary and not enough heat.Thus, the temperature of DPF 3 is risen to the superfluous heat higher than object regeneration temperature can be radiated the exhaust of flowing through DPF 3, with the temperature maintenance of DPF 3 in the object regeneration temperature.The target flow velocity of exhaust can replace with the target temperature of exhaust.

Perhaps, as shown in Figures 4 and 5,, can from the interior temperature distribution of DPF 3, derive the object gas flow velocity in order to keep the maximum temperature of DPF 3.In this method, handle DPF 3 via concentrated constant system (concentrated constant system), so that with respect to the method shown in Fig. 3, can accurately calculate the target flow velocity of exhaust.Unnecessary and not enough heat Δ Qmax is based on and is included in Pmax place, position because the total amount of heat Qrmax of the heat of heat that HC burning and PM burning produce and transfer at Pmax place, maximum temperature position, flow into the heat of exhaust Qfr of position Pmax, and to be used for the temperature maintenance at position Pmax place be that the heat Qbmax of object regeneration temperature calculates.Then, based on this unnecessary and not enough heat Δ Qmax and at the gas temperature Tfr with respect to position Pmax at upstream position Pfr and downstream position Prr place, the flow velocity that Trr calculates exhaust, so that maintain the temperature at Pmax place, position.

Thus, the flow velocity of exhaust that flows through DPF 3 is consistent with the target flow velocity of exhaust, so that the maximum temperature of DPF 3 is maintained at the object regeneration temperature, rises with the excess temperature of restriction DPF 3.Perhaps, when drive condition is changed to low-load from high load, perhaps when being changed to low speed at a high speed, calculating and be used for the temperature maintenance of DPF target flow velocity in the exhaust of preferred temperature.

Particularly, the gas flow rate control gear is adjusted air displacement from motor 1 according to the consistent such mode with the target flow velocity of exhaust of the flow velocity of the exhaust of flowing through DPF 3.For example, because the flow velocity of exhaust=flow through the flow velocity+EGR amount=live gas flow velocity+EGR amount of the exhaust of DPF 3, equal the live gas flow velocity so flow through the flow velocity of the exhaust of DPF 3.According to the deviation between live gas flow velocity and the object gas flow velocity, change the pressure loss by operated throttle valve 42, change the EGR amount by operation EGR valve 71, perhaps the spout blade by operation turbine 92 changes exhaust pressure loss and boost pressure, adjusting the driving power of turbine, the live gas flow velocity is maintained near the object gas flow velocity so that adjust suction pressure.In addition, have at turbine cartridge under the situation of electric motor, can adjust suction pressure by the speed of control electric motor.When exhaust energy was low relatively, electric motor can be adjusted air displacement effectively.

When the live gas flow velocity excessively reduced, suction pressure also excessively reduced to machine oil is imported cylinder, and this has caused some problems.For fear of such problem, limit the aperture of throttle valve 42, the aperture of EGR valve 71 and the aperture of spout blade according to suction pressure.

The rotational speed of motor 1 is depended in the increase of flowing through the air displacement of DPF 3.When the rotational speed of motor was in the low area such such as idling, the flow velocity of exhaust was difficult to be increased to the target flow velocity, made that excess temperature occurring rises.For fear of such problem, increase the rotational speed of motor 1 according to the slip rate (slip rate) of engine output shaft and vehicle, to obtain the required flow velocity of exhaust.As shown in Figure 6, when slip rate approximately was 100%, for example, when the clutch (not shown) was separated, the rotational speed of motor 1 was increased to the speed of obtaining the target flow velocity, thereby had limited the excess temperature rising.When the rotational speed of motor is excessively increased with respect to car speed, may cause some problems.Thus, should establish the upper limit of rotational speed increment.

With reference to figure 7 to 12, the operating process of ECU 6 will be described below.

Fig. 7 is a flow chart that the main operation that adds heat control of DPF 3 is shown.In step 100, estimate that DPF 3 temperature inside distribute.In this embodiment, set up ten temperature estimation points along flow line on DPF 3, in fact DPF 3 is divided into ten cells, and their temperature is measured to derive temperature distribution.Fig. 8 A is a flow chart that the process of estimating temperature distribution is shown.Step 101 to 110 in, calculate the heat budget of each cell.Calculate the heat budget of each cell by means of the heat budget model shown in Fig. 8 B.

In order to calculate the heat that cell receives, based on the heat output of DPF substrate and exhaust, the heat that HC produces, the heat of PM generation and the amount of thermal conduction that the cell substrate temperature is calculated each cell.Come the increment of accounting temperature in order to calculate the cell substrate temperature, be based on the heat that received and the thermal capacity of cell.Simultaneously, calculate the increment of HC amount, the increment and the O of PM quantity ₂Consume.Calculate about carry out this heat budget from first cell to the, ten cells, to calculate cell substrate temperature T1 to T10.Temperature T 1 is corresponding to the temperature of DPF 3 upstream portion, and temperature T 10 is corresponding to the temperature of DPF 3 downstream parts.The flow velocity of exhaust is based on that the checkout value of airometer 41 detects, and the upstream gas temperature of first cell is based on that the checkout value of first exhaust gas temperature sensor 51 detects, and the upstream HC of first cell amount is based on, and drive condition detects.

In the step 200 of Fig. 7, the flow velocity that is based on DPF pressure reduction and exhaust is estimated QAPM.Calculate DPF pressure reduction by means of differential pressure pickup 8, and calculate the flow velocity of exhaust based on the checkout value of airometer 41.In step 300, determine whether DPF 3 regenerates based on dpf temperature rising control program (not shown).In dpf temperature rising control program, between QAPM and predetermined regeneration-startup QAPM, compare.When QAPM surpasses regeneration-startup QAPM, open the regeneration sign, with the beginning heating operation.Open and answer in step 300 when being when being masked as, this process forwards step 400 to, wherein carries out gas flow rate based on the following step and controls.When answering in step 300 for not the time, this process finishes.

In step 400, based on the target airflow rate that dpf temperature distributes and calculates exhaust during dpf regeneration, it is called as GATRG.This GATRG is the flow velocity that the maximum temperature of DPF 3 is maintained its regeneration temperature.Fig. 9 is a Block Diagram that is used to calculate in the program of the targeted rate of regeneration period exhaust.In this program, calculate at position Pmax place owing to heat and the amount of thermal conduction that HC burns and PM burns and produces based on the cell substrate temperature of calculating in step 100, the HC amount that flows into DPF 3, the QAPM that in step 200, calculates.These heats are added in together, to calculate total amount of heat Qrmax.

Subsequently, calculate unnecessary and not enough heat Δ Qmax based on following equation (1).

ΔQmax＝Qrmax-Qbmax (1)

Thermal exposure (HRAQ) Qout is based on that following equation (2) calculates.

Qout＝Qrr-Qfr (2)

Qrr is illustrated in the heat that exhaust had at Prr place, position in the downstream of position Pmax.Qfr is illustrated in the heat that exhaust had at Pfr place, position of the upstream of position Pmax.

Temperature in the exhaust at position Pfr place represented by Tfr, represented by Trr in the temperature of the exhaust at position Prr place, and the flow velocity of exhaust represented by Mgas, and under the exhaust specific heat situation about being represented by Cp, sets up following equation (3), (4).

Qrr＝Cp×Mgas×Trr (3)

Qfr＝Cp×Mgas×Tfr (4)

When Qout equaled Δ Qmax, the flow velocity Mtrg of exhaust was represented by following equation (5).

Mtrg＝ΔQmax/{Cp×(Trr-Tfr)} (5)

The flow velocity Mtrg of exhaust is converted into the flow velocity of time per unit, with the target airflow rate GATRG that obtains in the regeneration period exhaust.

In step 500, near the target airflow rate GATRG that maintains the live gas flow velocity in the step 400 to be calculated, the live gas flow velocity is fed to change the aperture of throttle valve 42.Air inlet (live gas+EGR gas) flow velocity equals the flow velocity of exhaust (EGR gas+flow through the exhaust of DPF).Because the flow velocity of EGR gas is constant, can adjust by operated throttle valve so flow through the flow velocity of the exhaust of DPF, with increase/minimizing live gas flow velocity.

Figure 10 is a flow chart that the live gas feedback control procedure is shown.In step 501, live gas flow velocity GA reads from airometer 41.In step 502, suction pressure PIM reads from air inlet pressure sensor 43.In step 503, determine whether suction pressure PIM is lower than predetermined pressure PIM0.When answering in step 503 when being, this process forwards step 504 to, and wherein throttle position THR is retained as preceding value THROLD, to finish this process.

In step 505, calculate basic throttle position THRBASE by means of map based on engine rotary speed and desired torque.Be to control by PID to proofread and correct basic throttle position THRBASE, to calculate throttle position THR.

In step 5 06, obtain the deviation EGA between live gas flow velocity GA that in step 501, reads and the target airflow rate GATRG that in step 400, calculates.

EGA←GA-GATRG (6)

In step 507, come the integration amount of calculation deviation EGA based on previous integration amount.In step 508, come computing differential amount DEGA based on previous micro component.

IEGA(i)←IEGA(i-1)+EGA(i)……(7)

DEGA(i)←EGA(i)-EGA(i-1)……(8)

In step 509, previous throttle position THROLD is substituted by current throttle position THR.In step 510, calculate throttle position THR based on proportional gain KP, storage gain K1 and DG Differential Gain KD.

THR←THRBASE+KP·EGA+K1·IEGA+KD·DEGA (9)

In the step 600 of Fig. 7, determining whether to increase the exhaust flow velocity by the rotational speed that increases motor 1.Particularly, in the step 601 of Figure 11, determine whether clutch is separated.When clutch was separated, this process forwarded step 602 to, determined wherein whether the throttle position THR that calculates in step 510 is fully open position THRMAX.When answering in step 602 when being, this process forwards step 603 to.When clutch in step 601 is not separated, and when throttle position THR was not fully open position THRMAX, this process forwarded step 606 to.

In step 603, calculate the deviation delta GA between GA and the GATRG.In step 604, determine that deviation delta GA whether less than zero, this means the flow velocity deficiency of exhaust.When answering in step 604 when being, this process forwards step 605 to, and wherein engine speed increases and indicates that XNEUP is unlocked.When answering in step 604 for not the time, this process forwards step 606 to, indicates that wherein XNEUP is closed.

In the step 700 of Fig. 7, determine that whether sign XNEUP is for opening.When sign XNEUP when closing, this process end.When sign XNEUP when opening, this process forwards step 800 to, wherein the rotational speed of motor is increased, with the flow velocity of increase exhaust.In the step 801 of Figure 12, read car speed SPD.In step 802, the target rotational speed NETRG of calculation engine.Calculate target rotational speed NETRG based on following equation (10).

NETRG＝GATRG/(η×V) (10)

Wherein V represents engine displacement.

In step 803, calculate acceptable maximum engine speed NEMAX.Even acceptable maximum engine speed NEMAX is the engine speed that wherein vehicle does not quicken during clutch.Particularly, calculate the rotational speed that current car speed is maintained the motor of minimum gear ratio.In step 804, determine that whether NETRG is greater than NEMAX.When answering in step 804 when being, this process forwards step 805 to, wherein equals the rotational speed that the such mode of NETRG is come limiting engine according to NEMAX.Subsequently, this process forwards step 806 to.When answering in step 804 for not the time, this process forwards step 806 to.In step 806, adjust fuel injection amount, so that the rotational speed of motor equals target rotational speed NETRG.

As mentioned above, during regeneration GATRG, the flow velocity that flows through the exhaust of DPF can be adjusted to the object gas flow velocity of exhaust.Thus, can be radiated outside the DPF 3 as thermal exposure (HRAQ) Qout, be limited so that the excess temperature of DPF 3 rises, to avoid the fuel economy variation with the unnecessary and not enough corresponding heat of heat Δ Q.

Claims

1, a kind of exhaust gas filtering system that is used for internal-combustion engine (1), described internal-combustion engine (1) have and are used for catching the particulate filter (3) that is included in the particulate in the exhaust, and described exhaust gas filtering system comprises:

Temperature rising control gear (6) is used to increase the temperature of described particulate filter (3), and the temperature of described particulate filter (3) is remained on predetermined temperature, wherein

Described temperature rising control gear (6) comprising:

Object gas condition computing device, be used for being enough to described particulate filter (3) is maintained the unnecessary and not enough heat of described predetermined temperature, and calculating object gas condition is so that described unnecessary and not enough heat equals the heat that transmitted between described exhaust and described particulate filter (3) based on the temperature computation of total amount of heat that produces at described particulate filter (3) and described particulate filter (3); And

The gas flow rate control gear is used for according to obtaining the flow velocity that the such mode adjustment of described object gas condition is flow through the described exhaust of described particulate filter (3).

2, exhaust gas filtering system according to claim 1, wherein

Described object gas condition computing device calculates described object gas condition based on the temperature distribution of described particulate filter (3), so that keep the maximum temperature of described particulate filter (3).

3, exhaust gas filtering system according to claim 1, wherein

Described object gas condition is corresponding to the target flow velocity of described exhaust or the target temperature of described exhaust.

4, exhaust gas filtering system according to claim 3, wherein

Described object gas condition is corresponding to the target flow velocity of described exhaust, and

When being reduced one of at least of the driving load of the rotational speed of described internal-combustion engine (1) and described internal-combustion engine (1), described gas flow rate control gear with respect to the target flow velocity of described exhaust gradually with increasing correction flow through the flow velocity of the described exhaust of described particulate filter (3).

5, exhaust gas filtering system according to claim 3, wherein

The such mode of target flow velocity that described gas flow rate control gear equals described exhaust according to the flow velocity of the described exhaust of flowing through described particulate filter (3) is adjusted the air displacement from described internal-combustion engine (1).

6, exhaust gas filtering system according to claim 5, wherein

The aperture of the throttle position of described gas flow rate control gear by adjusting throttle valve (42), EGR control valve (7) and the rotary turbine power of pressurized machine (91,92) come one of at least the feedback control induction air flow ratio.

7, exhaust gas filtering system according to claim 6, wherein

Described gas flow rate control gear is set up and is monitored, so that keep suction pressure to be higher than predetermined value.

8, exhaust gas filtering system according to claim 5, wherein

Described gas flow rate control gear is adjusted air displacement from described internal-combustion engine (1) by the rotational speed that changes described internal-combustion engine (1) according to the slip rate between the live axle of output shaft and described internal-combustion engine (1) and car speed.